and where it says
ln -s '/etc/systemd/system/kexec-load.service' '/etc/systemd/system/kexec.target.wants/kexec-load.service'
is should say
ln -s '/lib/systemd/system/kexec-load.service' '/etc/systemd/system/kexec.target.wants/kexec-load.service'.

Do you agree?
I myself am still learning my way through systemd but I think using /lib/sytemd/system directory is upstream's compliant.